1. Field of the Invention
The present invention relates to a manufacturing method of an integrated capacitor to be integrated into a semiconductor device and such an integrated capacitor, more particularly, to a manufacturing method of an integrated capacitor having a high dielectric constant capacitor insulating film and the integrated capacitor.
2. Description of the Related Art
A semiconductor memory such as a DRAM which is an integrated circuit requires, as an integrated element, a capacitor (electrostatic capacitance element) for the accumulation of charge in addition to a transistor. With an increase in memory size from 256 Mb to 512 Mb and further to a gigabit-class memory size, an improvement in the degree of integration of elements is inevitably demanded. To improve the degree of integration, an integrated capacitor having a structure (trench capacitor) in which a hole is formed in a semiconductor substrate, a capacitor insulating film is formed on an inner face of the hole, and an electrode material is embedded in the hole is already used. The capacitor thus structured is described, for example, in Japanese Patent Laid-open Application No. 2003-282734 (Patent Document 1). According to this, it is possible to form a higher electrostatic capacitance capacitor with smaller dimensions as a plan view.
To enable the trench capacitor to cope with higher integration, measures to reduce an area in the plan view and secure an electrostatic capacitance as the capacitor are needed. As one of these measures, it is conceivable to use a high dielectric constant film as the capacitor insulating film. In this case, a point to consider is how the high dielectric constant film is formed at high quality in a desired region. The high dielectric constant film has a different property from a low dielectric constant film (such as silicon oxide), whereby a processing (etching) method different from a conventional one is needed. Incidentally, etching of a material which serves as the high dielectric constant film is described, for example, in Japanese Patent Laid-open Application No. 2003-234325 (Patent Document 2).                [Patent Document 1] JP-A 2003-282734        [Patent Document 2] JP-A 2003-234325        
A point to notice when a high dielectric constant film is used as a capacitor insulating film is a reduction in leakage current. This is because, if the leakage current is large, a basic characteristic as a capacitor cannot be secured. It is understood here that to reduce the leakage current, it is useful that a high dielectric constant material is heat-treated and crystallized. However, the crystallized high dielectric constant film is very hard to etch in terms of processability. Accordingly, it is difficult to manufacture an integrated capacitor with a trench structure using the high dielectric constant film.